1. The latent period of the skeletal muscle that was tested in this lab simulation wasa. about 1 second.b. less than 1 msec. c. between 2-3 msec.d. variable, depending on the voltage that was applied to it.

2. True or False: Another name for a muscle cell is “myofibril.”

3. The largest active force that could be generated in the muscle is Activity 1 was _______ grams.

8. Does the duration of the latent period change with different stimulus voltages?

9. At the threshold stimulus, do sodium ions start to move into or out of the cell to bring about the membrane depolarization?

ACTIVITY 2: The Effect of Stimulus Voltage on Skeletal Muscle Contraction10. The threshold voltage for the muscle in this lab simulation was ________ volts. When that voltage was used to stimulate the muscle, ________ grams of active force were generated.

11. True or False: In a resting skeletal muscle cell, most of the calcium ions freely move through the cytoplasm of the cell.

12. Describe the effect of increasing stimulus voltage on isolated skeletal muscle. Specifically, what happened to the muscle force generated with stronger electrical stimulations and why did this change occur?

13. How is this change in whole-muscle force achieved in vivo (eg. in the human body)?

14. What happened in the isolated skeletal muscle when the maximal voltage was applied?

ACTIVITY 3: The Effect of Stimulus Frequency on Skeletal Muscle Contraction15. True or False: There is no limit to the amount of force that a skeletal muscle can generate if it is stimulated by a high enough voltage at a very high frequency.

16. The chemical ion or molecule that is primarily responsible for initiating the contraction of a muscle fiber isa. Na+b. K+ c. Ca2+d. ADP

17. What is the difference between stimulus intensity and stimulus frequency?

18. In this experiment you observed the effect of stimulating the isolated skeletal muscle multiple times in a short period with complete relaxation between the stimuli. Describe the force of contraction with each subsequent stimulus. Is this called treppe or wave summation?

19. How did the frequency of stimulation affect the amount of force generated by the isolated skeletal muscle when the frequency of stimulation was increased such that the muscle twitches did not fully relax between subsequent stimuli? Is this called treppe or wave summation?

20. To achieve an active force of 5.2 g, did you have to increase the stimulus voltage above 8.5 volts? If not, how did you achieve an active force of 5.2 g?

ACTIVITY 4: Tetanus in Isolated Skeletal Muscle21. When stimuli were applied to the muscle frequently enough to cause a plateau in the amount of force generated, a state known as ____________ ____________ occurs.

22. Why do children (and adults) receive an immunization (actually several!) called a “tetanus shot”?a. This will prevent the development of muscle fatigue when she/he becomes an athlete.b. The person will then be able to develop the maximum amount of force from each and every muscle in her/his body.c. To prevent the development of a condition called “lockjaw” that can develop from a specific bacterial infection.d. This will a reminder to her/him to keep the skin washed and clean when she/he is outside playing.

23. The maximal tetanic tension of the muscle in this simulation was _________ grams.

24. Describe how increasing the stimulus frequency affected the force developed by the isolated whole skeletal muscle in this activity.

25. Indicate what type of force was developed by the isolated skeletal muscle in this activity at the following stimulus frequencies: at 50 stimuli/second, at 140 stimuli/second, and above 146 stimuli/second.

26. Beyond what stimulus frequency is there no further increase in the peak force? What is the muscle tension called at this frequency?

ACTIVITY 5: Fatigue in Isolated Skeletal Muscle27. True or False: The primary reason for muscle fatigue is the buildup of Ca2+ ions in the muscle fiber.

28. If an intervening rest period is imposed on active muscle,a. it will then be able to generate much more force.b. the development of fatigue will be delayed. c. muscle hypertrophy can be prevented.d. muscle atrophy can be prevented.

29. When a skeletal muscle fatigues, what happens to the contractile force over time?

30. What are some proposed causes of skeletal muscle fatigue?

31. Turing the stimulator off allows a small measure of muscle recovery. Thus, the muscle will produce more force for a longer time period if the stimulator is briefly turned off than if the stimuli were allowed to continue without interruption. Explain why this might occur.

32. List a few ways that humans could delay the onset of fatigue when they are vigorously using their skeletal muscles.

ACTIVITY 6: The Skeletal Muscle Length-Tension Relationship33. In a force-length graph, a. the muscle length is the independent variable. b. the amount of force generated is the dependent variable.c. both active and passive forces must be considered.d. All the above are correct.

34. According to your lab manual, the protein titin is the primary cause of _________ __________.

35. In this lab simulation, the muscle length of _______ mm was able to generate the largest active force.

42. The fastest muscle contraction velocity in this simulation was approximately ________ mm/msec.

43. True or False: A muscle that is contracting isometrically will fatigue much slower than one that is contracting isotonically.

44. If you were using your biceps muscles to curl a 7kg dumbbell, when would your muscles be contracting isotonically?

45. Explain why the latent period became longer as the load became heavier in the experiment.

46. Explain why the shortening velocity became slower as the load became heavier in this experiment.

47. Explain why it would take you longer to perform 10 repetitions lifting a 10kg weight than it would to perform the same number of repetitions with a 5kg weight.

48. Describe what would happen in the following experiment: A 2.5g weight is attached to the end of the isolated whole skeletal muscle used in these experiments. Simultaneously, the muscle is maximally stimulated by 8.5 volts and the platform supporting the weight is removed. a. Will the muscle generate force?b. Will the muscle change length?c. What is the name for this type of contraction?

DTRUE180 g/molTEMPERATURE AND SIZE OF MOLECULESUREA UNABLE TO DIFFUSE DUE O SATURATIONGLUCOSE ABLE TO DIFFUSE BUT ALBUMIN NOT ABLE TO DIFFUSESODIUM CHLORIDE, UREA, GLUCOSE, ALBIMINAnswersFALSEDFALSESAME - BOTH TRANSPORT DOWN THE CONCENTRATION GRADIENT.DIFFER – FACILITATED DIFFUSIONR EQUIRES A MEMBRANE BOUND CARRIER PROTIEN TO ASSIST IN TRANSPORT, THIS IS NOT FOUND IN SIMPLE DIFFUSION.

THE GREATER THE CONCENTRATION DIFFERENCE BETWEEN BOTH SIDES OF THE MEMBRANE, THE GREATER THE FACILITATED DIFFUSION.NaCL WILL HAVE NO EFFECT ON GLUCOSE DUE TO SATURATIONAnswersTRUEB

CINCREASING NON-DIFFUSIBLE PARTICLES INCREASES OSMOTIC PRESSURE. IF SOLUTES ABLE TO DIFFUSE THEN NO SOMOTIC PRESSURE WOULD BE BUILT UP. OSMOTIC PRESSURE WOULD BE ZERO IF ALBIUMIN CONCENTRATION WAS THE SAME ON BOTH MEMBRANE SIDES. SIMILAR – BOTH INVOLVE THE MOVEMENT OF A SUBSTANCE TO AN AREA WITH A HIGHER CONCENTRATION TO LOWER (ALONG OR DOWN ALSO) CONCENTRATION GRADIENT. DIFFER – DIFFUSION MOVES PARTICLES AND IONS. OSMOSIS ONLY MOVES WATER.OSMOSIS IS THE DIFFUSION OF SOLVENT (WATER). WATER IN THIS CASE DIFFUSES TO THE SIDE OF THE MEMBRANE THAT HAS THE HIGHEST CONCENTRATION OF SOLUTES. I PREDICTED INCORRECTLY AND THE PRESSURE INCREASED ON THE LEFT.AnswersDFALSEINCREASING THE PORE SIZE INCREASES THE FILTRATION RATE AS MORE FLUIDS AND SOLUTES CAN PASS THROUGH THE MEMBRANE.NONE APPEARED. SOLUTIONS TOO LARGE TO PASS THROUGH.BLOOD PRESSURE INCREASE CAUSES FILTRATION RATE INCREASE. NO INCREASE IN SOLUTES CONCENTRATION DUE TO PORE SIZES NOT INCREASING.AnswersDFALSEE3 IONS ARE EJECTED FOR EVERY 2K THAT ARE ADDED. K HANG OUTSIDE THE CELL UNLESS ACTIVELY TRANSPORTED INSIDE.SAME - BOTH TRANSPORT DOWN THE CONCENTRATION GRADIENT.DIFFER – FACILITATED DIFFUSIONR EQUIRES A MEMBRANE BOUND CARRIER PROTIEN TO ASSIST IN TRANSPORT, THIS IS NOT FOUND IN SIMPLE DIFFUSION.

THE GREATER THE CONCENTRATION DIFFERENCE BETWEEN BOTH SIDES OF THE MEMBRANE, THE GREATER THE FACILITATED DIFFUSION.NaCL WILL HAVE NO EFFECT ON GLUCOSE DUE TO SATURATIONAnswersTRUEB

CINCREASING NON-DIFFUSIBLE PARTICLES INCREASES OSMOTIC PRESSURE. IF SOLUTES ABLE TO DIFFUSE THEN NO SOMOTIC PRESSURE WOULD BE BUILT UP. OSMOTIC PRESSURE WOULD BE ZERO IF ALBIUMIN CONCENTRATION WAS THE SAME ON BOTH MEMBRANE SIDES. SIMILAR – BOTH INVOLVE THE MOVEMENT OF A SUBSTANCE TO AN AREA WITH A HIGHER CONCENTRATION TO LOWER (ALONG OR DOWN ALSO) CONCENTRATION GRADIENT. DIFFER – DIFFUSION MOVES PARTICLES AND IONS. OSMOSIS ONLY MOVES WATER.OSMOSIS IS THE DIFFUSION OF SOLVENT (WATER). WATER IN THIS CASE DIFFUSES TO THE SIDE OF THE MEMBRANE THAT HAS THE HIGHEST CONCENTRATION OF SOLUTES. I PREDICTED INCORRECTLY AND THE PRESSURE INCREASED ON THE LEFT.AnswersDFALSEINCREASING THE PORE SIZE INCREASES THE FILTRATION RATE AS MORE FLUIDS AND SOLUTES CAN PASS THROUGH THE MEMBRANE.NONE APPEARED. SOLUTIONS TOO LARGE TO PASS THROUGH.BLOOD PRESSURE INCREASE CAUSES FILTRATION RATE INCREASE. NO INCREASE IN SOLUTES CONCENTRATION DUE TO PORE SIZES NOT INCREASING.AnswersDFALSEE3 IONS ARE EJECTED FOR EVERY 2K THAT ARE ADDED. K HANG OUTSIDE THE CELL UNLESS ACTIVELY TRANSPORTED INSIDE.THEY WERE EJECTED BY THE CELLS (ACTIVE TRANSPORT)SOLUTE PUMPSGLUCOSE TRANSPORTED BY FACILITATED DIFFUSION. SOLUTIONS WERE LIPID INSOLUBLE AND TO LARGE TO PASS THROUGH THE MEMBRANE PORES

This topic is currently locked from adding new posts. Only administrators and moderators can reply. If you'd like to contribute to this topic, start a new thread and make reference to this one. Otherwise, contact a moderator for more options.

Control Panel

Click to Ask a Question

612 Students and 27 members are standing by to answer your homework problems, free.
So far today, 143 guests have joined.